Tim Downie wrote:
gmw wrote:
I have just used a photographic exposure meter to compare the light
output of a CFL bulb with various pearl light bulbs.

The CFL is a 20W bulb claimed to be equivalent to a 100W bulb. It has
had about 1 year of evening use.
Its measured light output is a little LESS than a 60W 2000h pearl bulb
rated at 555 lumerns, and ~40% of a 100W 2000hr bulb.
Power ratio for the same light output is thus 1/3 not 1/5. This is a
66% over claim in this case.

The small print on the CFL package says it is equivalent to a 1000h
"soft colour" bulb. This is presumably much lower efficiency than
normal pearl bulbs. This claim is therefore presumably accurate but
misleading.

Having replaced several 100W pearl light bulbs with "100W" CFLs, we
have reverted to pearl in all but one room.

These misleading claims must be understood and ruled out. CFLs are not
yet ready to replace conventional bulbs. The calculated efficiency
gains are greatly exaggerated.

Please copy to naive environmentalists, band-wagon jumpers, and
government ministers.

I've carped about this for years. The claimed outputs are nowhere near 5
times the rated wattage. When Which? did a test on CFLs I wrote to them
pointing this out and asking if they could rate bulbs by their actual
output, not their claimed one.

My pleas fell on deaf ears. Hope you have better luck than me in getting
someone to listen.

Tim


Totally agree that light for light CFL bulbs not only are overstated but
won't make a blindest bit of difference to the planet.

They do however last long enough to be cost effective. Replacement bulbs
add up to a lot of money..